Anatomy and Physiology I Bio 130 Professor Peter Smith D.P.T, ATC

Overview of Anatomy and Physiology Anatomy – the study of the structure of body parts and their relationships to one another Physiology – the study of the function of the body’s structural machinery Cytology – study of the cell Histology – study of tissues

Chemical level Atoms combine to form molecules Cellular level Cells are made up of molecules Tissue level Tissues consist of similar types of cells 5 Organ system level Organ systems consist of different organs that work together closely Organ level Organs are made up of different types of tissues 6 Organismal level The human organism is made up of many organ systems Atoms Molecules Smooth muscle cell Smooth muscle tissue Connective tissue Smooth muscle tissue Epithelial tissue Blood vessel (organ) Heart Blood vessels Cardiovascular system Levels of Structural Organization

Organ Systems Interrelationships Nutrients necessary for energy production for all the cells in the body are absorbed in the digestive system. O 2 and CO 2 are exchanged by the respiratory system and distributed throughout the blood by the circulatory system. Metabolic wastes are eliminated by the urinary and respiratory systems

Homeostasis Homeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside world The internal environment of the body is in a dynamic state of equilibrium –There is a tight regulation of hormones (chemical messages), changes is body temperature and the nervous system. –The body is designed to maintain homeostasis! Diets fail because calorie restriction can promote a rapid drop in body weight. Your physiology sees this as a threat to your survival. To restore homeostasis metabolism is reduced.

Stimulus: Produces change in variable Change detected by receptor Input: Information sent along afferent pathway to 5 Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis Variable (in homeostasis) Imbalance Receptor (sensor) Control center 4 Output: Information sent along efferent pathway to Effector Homeostatic Control Mechanisms

Negative Feedback In negative feedback systems, the output shuts off the original stimulus.

Negative Feedback When the body temperature is higher than the set point the blood vessels dilate bring the blood closer to the skin. Evaporated sweat cools the body When the body is cold blood is shunted toward the internal organs way from the skin to minimize heat lose. Shivering creates heat as a byproduct of muscle metabolism

Negative Feedback

Positive Feedback In positive feedback systems, the output enhances or exaggerates the original stimulus Example: Regulation of blood clotting Figure 1.6

Homeostatic Overview Under normal circumstances the body’s homeostatic controls are maintained by negative feedback loops. Diseases are often made worse because of failure of the normal negative feedback mechanisms. The creation of positive feedback loops that further drive the body away from its homeostatic mechanisms. Example: –Diseased lungs reduce the body’s ability to bring in oxygen to the cells. The body tries to adapt by make more oxygen carrying red blood cells. The result is thicker blood. This makes the heart work harder and even get larger. The larger heart put pressure on the lungs.